title: Type 2A Koebner phenomenon in vitiligo is distinct from other subtypes: observations from an Indian cohort.
abstract: BACKGROUND
  Koebner phenomenon (KP) in vitiligo has been redefined and classified recently.
  
  
  OBJECTIVE
  To study the clinical characteristics of various grades of KP.
  
  
  METHODS
  In this prospective cross-sectional study, 202 patients with vitiligo were studied between January 2011 and December 2012 for the presence of KP. Based on the new Vitiligo European Task Force guidelines, KP was classified as type 1-3 and grades Ι-IV. Disease characteristics were studied in the various groups and subgroups based on the presence of KP.
  
  
  RESULTS
  Koebner phenomenon was seen in 130 of 202 patients. The mean age of patients showing KP was 23.9 ± 13.6 years, compared with 19.3 ± 12.4 years for patients not showing KP (P = 0.02). The mean body surface area involved in the KP-positive group was 4.6 ± 5.6%, vs. 1.5 ± 1.1% in the KP-negative group (P = 0.001). Fifty-five patients experiencing KP received low-dose dexamethasone oral minipulse therapy compared with nine of those who did not (P = 0.01). Of the 130 patients with KP, grade Ι KP was seen in 32, grade II KP in 116, grade III KP in 22 and grade IV KP in 16. There was a significant difference between type 1 and type 2A KP, and between type 2A and type 2B KP. In contrast, type 1 and type 2B KP were found not to be significantly different and had a good degree of correlation.
  
  
  CONCLUSIONS
  Patients with KP have a significantly higher age at onset, more extensive cutaneous involvement and are more likely to receive systemic steroids for disease control. Type 2A disease was found to be distinct from the other subtypes.
authors.affiliation: Department of Dermatology, Venereology, and Leprology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India.
authors.forename: A J
authors.initials: AJ
authors.lastname: Kanwar
authors.forename: R
authors.initials: R
authors.lastname: Mahajan
authors.forename: D
authors.initials: D
authors.lastname: Parsad
mesh_terms: D000328:Adult; D017668:Age of Onset; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000208:ethnology; D008297:Male; D011446:Prospective Studies; D014820:Vitiligo / Q000208:ethnology / Q000473:pathology*; D055815:Young Adult